From c73e59341dde78c84e110f03ed5ada85cb3aaba9 Mon Sep 17 00:00:00 2001
From: Logan oos Even <46396513+Logan007@users.noreply.github.com>
Date: Mon, 8 Feb 2021 20:55:11 +0545
Subject: [PATCH] made gratuitous arp being sent at the right time (#635)

---
 src/edge.c       |  3 +--
 src/edge_utils.c | 16 ++++++++++------
 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/src/edge.c b/src/edge.c
index 5be7cc0..1c61e1c 100644
--- a/src/edge.c
+++ b/src/edge.c
@@ -950,7 +950,7 @@ int main (int argc, char* argv[]) {
         runlevel = 2;
     }
 
-    eee->last_sup = 1; /* to prevent gratuitous arp packet */
+    eee->last_sup = 0; /* if it wasn't zero yet */
     eee->curr_sn = eee->conf.supernodes;
 
     while(runlevel < 5) {
@@ -1072,7 +1072,6 @@ int main (int argc, char* argv[]) {
     eee->last_sweep = now_time - SWEEP_TIME + 2 * BOOTSTRAP_TIMEOUT;
     eee->sn_wait = 1;
     eee->last_register_req = 0;
-    eee->last_sup = 0; /* to allow gratuitous arp packet after regular REGISTER_SUPER_ACK */
 
 #ifndef WIN32
     if(eee->tuntap_priv_conf.daemon) {
diff --git a/src/edge_utils.c b/src/edge_utils.c
index b26fd7b..cb2d6fb 100644
--- a/src/edge_utils.c
+++ b/src/edge_utils.c
@@ -2229,14 +2229,18 @@ void readFromIPSocket (n2n_edge_t * eee, int in_sock) {
                             }
                         }
 
-                        if(!eee->last_sup) {
-                            // indicates successful connection between the edge and a supernode
-                            traceEvent(TRACE_NORMAL, "[OK] Edge Peer <<< ================ >>> Super Node");
-                            // send gratuitous ARP only upon first registration with supernode
-                            send_grat_arps(eee);
+                        // update last_sup only on 'real' REGISTER_SUPER_ACKs, not on bootstrap ones (null_mac)
+                        // this allows reliable in/out PACKET drop if not really registered with a supernode yet
+                        if(!is_null_mac(ra.edgeMac)) {
+                            if(!eee->last_sup) {
+                                // indicates successful connection between the edge and a supernode
+                                traceEvent(TRACE_NORMAL, "[OK] Edge Peer <<< ================ >>> Super Node");
+                                // send gratuitous ARP only upon first registration with supernode
+                                send_grat_arps(eee);
+                            }
+                            eee->last_sup = now;
                         }
 
-                        eee->last_sup = now;
                         eee->sn_wait = 0;
                         eee->sup_attempts = N2N_EDGE_SUP_ATTEMPTS; /* refresh because we got a response */